Sensor product for electric field sensing

ABSTRACT

A sensor product web for electric field sensing. The sensor includes a substrate, sequential electrically conductive areas on a surface of the substrate, conductors, an output connected to one of the electrically conductive areas by one of the conductors, a dielectric layer arranged on top of the conductors, and an electrically conductive layer arranged on top of the dielectric layer on a same surface of the substrate as the electrically conductive areas, the dielectric layer being discontinuous at the conductor which is in contact with the electrically conductive area.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/631,893 filed Nov. 19, 2007, which is the national phaseunder 35 U.S.C. §371 of PCT/FI2005/000312 filed 5 Jul. 2005 and claimspriority to U.S. provisional patent application No. 60/585,711 filed 6Jul. 2004.

FIELD OF INVENTION

The present invention relates to a sensor product. The sensor productcan be used in computer user interfaces, occupant or passengermonitoring systems, e.g. in keyboards, smart air bag systems, and floorconstructions.

BACKGROUND

Electric field sensing refers to a method for determining positions,movements and geometries of objects on the basis of disturbances whichthey cause to a surrounding electric field.

Most of the pioneering work in electric field sensing can be attributedto nature. Electric fields are, used by various aquatic animals forsensing their environment, especially in the dark, muddy waters wherelight is scarce (Bastian J., Electrosensory Organism, Physics Today,pages 30-37, February 1994).

Professor Neil Gershenfeld's group at the MIT Media Laboratory hasapplied electric field sensing for measurements of position, shape andsize since the early 1990's. Prof. Gershenfeld's group has, for example,developed an interface for human-computer interaction based on electricfield sensing and charge source tomography.

In the University of Queensland there has also been studied electricfield sensing. A low frequency electric field is generated in order toinduce a current and the induced current is measured at receiving nodes.When an object interferes with the electric field, the capacitance ofthe environment is altered and the received current values are changed.By modeling the effect of a foreign body in the field, thecharacteristics of this body can be derived by the current valuesobtained (O'Brien Christopher John, Electric Field Sensors for NonContact Graphical Interfaces, Thesis, School of information technologyand Electrical Engineering, University of Queensland, 2001).

A critical component of any intelligent environment is a user interface.All user interfaces, such as keyboard, mouse, touchpad and touch screen,have their pros and cons. Most of the user interface devices aretypically relatively fragile and expensive, have limited scalability forlarge areas, and are poorly applicable for use outdoors or in harshenvironments. Charge source tomography (CST) is a method for sensing aninteraction between a user and flat or curved surfaces which are madesensitive by an addition of a conformable resistive sheet that is ableto create electric fields. The CST-based user interface device comprisesa resistive sheet, peripheral electrodes, and a current/voltagecontroller. During operation, a controller applies voltage patterns topoints on the perimeter of the resistive sheet and measures the currentsthat arise as a consequence. The user appears in this system as acapacitive load localized to some region of the resistive sheet. (Post ERehmi, Agarwal Ankur, Pawar Udai, and Gershenfeld Neil, ScalableInteractive Surfaces via Charge Source Tomography, 2nd InternationalConference on Open Collaborative Design of Sustainable Innovation. Dec.1-2, 2002, Bangalore, India; Strachan John Paul, Instrumentation andAlgorithms for Electrostatic Inverse Problems, Masters Thesis,Massachusetts Institute of Technology, Cambridge, Mass., 2001.)

The CST enables an interactive surface to be used with bare handswithout touching. Furthermore, the CST makes it possible to manufacturelow-cost and mechanically robust user interface devices that arescalable and easy to embed into a variety of surface materials andshapes.

SUMMARY OF THE INVENTION

A general object of the invention is to provide a cost-effective sensorproduct for touch-free interfaces. The sensor product may compriseseveral layers attached to each other.

A specific object is to provide a sensor product that comprises an arrayor matrix of electrically conductive areas and conductors on a flexiblesubstrate, and a method for manufacturing it. The electricallyconductive areas form sensor elements. In this arrangement the sensedarea is scalable by increasing the number of the electrically conductiveareas. It is also possible to increase the area of the electricallyconductive areas and the distances between them at the expense ofresolution.

Another specific object is to provide a sensor product, also known as aresistive sheet laminate, comprising an electrically conductive area,which includes a resistive sheet and peripheral electrodes on a flexiblesubstrate, and a method for manufacturing it. In this arrangement thearea of the resistive sheet is scalable without changing the number ofelectrodes. A further specific object is to provide ways of adjustingthe conductivity of the resistive sheet.

The present invention also provides conductors between the electricallyconductive areas and the output and protective layers if desired. Theconductors may be made using the same material and manufacturing processas the electrodes. However, in order to maximize the cost efficiency insome cases it might be advantageous to use a different material andprocess for electrodes and conductors. The manufacturing process stepsof the present invention also enable utilization of a continuousroll-to-roll process.

This invention is not limited to the CST-based user interfaces, but mayalso be applied to similar sensor technologies, such as capacitivesensors and electrical impedance tomography.

A characteristic feature of the products in accordance with the presentinvention is a layered structure that comprises conducting sensorelements, or a resistive sheet and peripheral electrodes as analternative structure. Optional features are that said layered structurealso comprises conductors between the electrically conductive areas andthe output and protective layers.

The sensor product of the invention can be used, for example, foruser-computer interfaces and for sensing bodies. The touch-freeoperation, scalability, flexibility, robustness, and low-costmanufacturing enable a large variety of applications. In connection withthe user-computer interfaces, the sensor product can be a substitute fora keyboard, a mouse, a touch pad, or a touch screen, or the sensorproduct can be used in parallel with them. The sensor product can beused as smart blackboards, whiteboards, or flipcharts. Further, thesensor product can be used at info kiosks, cash machines, and inindustrial control panels. The sensor product can be hiddenin/on/behind/under construction elements, for example walls, panels,boards, tables, displays, windows, or posters.

In the body sensing the sensor product can be used for identifying thepresence, orientation, location, or movement of a body. The sensorproduct can be hidden as a sensor mat into/onto/under/behind floors,walls, roofs, or seats. The sensor product can be used for car passengersensing for example for air bag control, or air condition control. Otheruses of the sensor product include safety and security applications,access control systems, burglar alarm systems, safety and monitoringsystems for aged and disabled people, building automation, lightingcontrol, or air conditioning.

The sensor product of the invention comprises a substrate, an output, atleast one electrically conductive area on the surface of the substrateand at least one conductor between the at least one electricallyconductive area and the output. The electrically conductive area maycomprise sub-areas, whose electrical conductivity differs from eachother, or the electrically conductive area may have substantially thesame conductivity throughout the whole area.

The substrate is a sheet-like material, or a film. The substratecomprises plastic material, or fibrous material in a form of a nonwovenfabric, fabric, paper, or board. Suitable plastics are, for example,plastics comprising polyethyleneterephtalate (PET), polypropylene (PP),or polyethylene (PE). The substrate is preferably substantially flexiblein order to conform with other surfaces on which it is placed. Besidesone layer structure, the substrate can comprise more layers attached toeach other. The substrate may comprise layers that are laminated to eachother, extruded layers, coated or printed layers, or mixtures of those.

The sensor product is provided with an output in order to make itpossible to connect the output to control electronics. Measurementvoltages and control output currents can be fed through the output. Inpractice the output can comprise conductors next to each other. Astandard connector used in common electronic applications (e.g.Crimpflex®, Nicomatic SA, France) can be added to the output.

At least one electrically conductive area and at least one conductorbetween the electrically conductive area and the output is formed on thesurface of the substrate. According to one embodiment of the invention,the sensor product comprises an electrically conductive area whichincludes a resistive sheet and at least one peripheral electrode on aflexible substrate. Usually there are more than one electrodes andconductors because accurate sensing requires several electrodes. Thenumber of electrodes also depends on number of variables to be solved.The electrodes and the conductors comprise metal, electricallyconductive carbon, or electrically conductive polymers. Common metals inthat use are aluminium, copper and silver. Electrically conductivecarbon may be mixed in a medium in order to manufacture an ink or acoating. Examples of electrically conductive polymers are polyacetylene,polyaniline and polypyrrole. The electrodes and the connectors can bemade, for example, by etching or printing.

The resistive sheet is preferably a rectangular area formed on thesurface of the substrate. The term “resistive” refers to the fact thatthe resistive sheet typically possesses a lower electrical conductivitythan the electrodes and the conductors. The resistive sheet has anelectrical resistance in a range between 100 kΩ and 10 MΩ, preferably ina range between 0.9 MΩ and 1.1 MΩ. The resistance value is measuredbetween electrodes which are placed on the opposite sides of therectangle which forms the resistive sheet (HP 34401 A multimeter, T=23°C., RH=50%, U=1.8V). In other words, the resistance value must be in thepredetermined range independent from the size of the resistive sheet,and by adjusting the raw materials of the resistive sheet the resistancevalue can be adjusted to a desired level.

The resistive sheet comprise electrically conductive material, and itcan be a printed layer, a coated layer, a plastic layer, or a fibrouslayer. As an electrically conductive element the resistive sheet maycomprise conductive carbon, metallic layers, particles, or fibers, orelectrically conductive polymers, such as polyacetylene, polyaniline, orpolypyrrole. When a transparent sensor product is desired, electricallyconductive materials like ITO (indium tin oxide), PEDOT(poly-3,4-ethylenedioxythiophene), or carbon nanotubes can be used. Forexample, the carbon nanotubes can be used in coatings which comprise thenanotubes and polymers. The same electrically conductive materials alsoapply to the electrodes and the conductors.

According to another embodiment of the invention, the sensor productcomprises an array or matrix of electrically conductive areas on aflexible substrate. The electrically conductive areas do not necessarilycomprise separate electrodes but the electrically conductive area maycomprise the same material throughout the electrically conductive area.In that embodiment it is advantageous that the electrically conductiveareas have a high electrical conductivity.

The electrically conductive area can be of metal, electricallyconductive carbon, or electrically conductive polymer. Common metals forthat use are aluminium, copper and silver. Electrically conductivecarbon may be mixed in a medium in order to manufacture an ink or acoating. Examples of the electrically conductive polymers arepolyacetylene, polyaniline and polypyrrole. Although there may bedifference in the electrical conductance, the same electricallyconductive materials, which are mentioned in connection with theresistive sheet, also apply to the electrically conductive areas andconductors of the product according to the second embodiment. Theelectrically conductive area can be made, for example, by etching orprinting.

There are various techniques available for forming the electricallyconductive areas and the conductors, for example etching, screenprinting (flat bed or rotation), gravure, offset, flexography, inkjetprinting, electrostatography, electroplating and chemical plating.

On the surface of the substrate there may be a protecting layer whichcan be any flexible material, for example paper, board, or plastic, suchas PET, PP, or PE. The protecting layer may be in the form of anonwoven, fabric, or a foil. A protective dielectric coating, forexample an acrylic based coating, is possible.

BRIEF DESCRIPTION OF THE FIGURES

In figures,

FIG. 1 a shows a top view of a sensor product,

FIG. 1 b shows a cross section of the sensor product of FIG. 1,

FIG. 2 a shows a top view of a potential sensor product structure forpassenger sensing applications used in smart air bag systems,

FIG. 2 b shows a cross-sectional view of the sensor product structure ofFIG. 2 a,

FIG. 3 a shows a top view of a sensor product for monitoring conductiveobjects,

FIG. 3 b shows a cross-sectional view of the sensor product of FIG. 3 a,

FIG. 4 a shows a top view of a sensor product for monitoring conductiveobjects,

FIG. 4 b shows a cross-sectional view of the sensor product of FIG. 4 a,

FIG. 4 c shows a top view from a junction of conductors and adielectric/conductive bridge, and

FIG. 4 d shows a cross-sectional view from a junction of conductors anda dielectric/conductive bridge.

DETAILED DESCRIPTION

FIG. 1 a shows a top view and FIG. 1 b shows a cross section of a sensorproduct 7 (section A-A). Electrodes 2 and conductors 3 are formed on asurface of a substrate 6. The conductors 3 connect the electrodes 2 viaan output 8 to a connector 5. A resistive sheet 4 overlaps theelectrodes 2. A protecting layer 1 is formed on top of the substrate insuch a manner that the electrodes 2, conductors 3 and the resistivesheet remain between the substrate 6 and the protecting layer 1.

FIG. 2 illustrates a potential sensor product structure for passengersensing applications used in smart air bag systems. FIG. 2 a shows a topview and FIG. 2 b shows a cross-sectional view (section B-B). The sensorproduct comprises a substrate 24 on the surface of which are formedelectrically conductive areas which form sensor elements 21. The sensorelements 21 are connected to an output 26 via conductors 25. The output26 connects the sensor product 27 to the electronics. Number 23 denotesventilation holes. On top of the substrate there is a protecting layer22.

FIG. 3 illustrates a sensor product for monitoring electricallyconductive objects, for example movement and location of a human body.This application is mainly used for monitoring aged and disabled people.FIG. 3 a shows a top view and FIG. 3 b shows a cross-sectional view(section C-C). The sensor product 35 comprises a substrate 34,electrically conductive areas which form sensor elements 31 formed onthe surface of the substrate 34 and conductors 33 connecting the sensorelements 31 to an output. On top of the substrate 34 there is aprotecting layer 32.

FIG. 4 a shows a top view of a sensor product for monitoringelectrically conductive objects, for example movement and location of ahuman body and FIG. 4 b shows a cross-sectional view of the sensorproduct of FIG. 4 a (section D-D). This application is mainly used formonitoring aged and disabled people. The sensor product can bemanufactured as a continuous web in a roll-to-roll process. The sensorproduct comprises a substrate 44, an electrically conductive area 41 andconductors 43 on the surface of the substrate 44. On the surface of thesubstrate 44 there is a protecting layer 42. The electrically conductivearea 41 and the conductors 43 remain between the substrate 44 and theprotecting layer 42. Number 45 denotes a dielectric bridge onto whichsurface an electrically conductive bridge is printed. In this manner thesensor product can be manufactured as a continuous roll, and thecontinuous roll can be cut at a desired point. Number 48 denotes anoutput but the output can be formed at any cutting point, for example atsection D-D shown in FIG. 4 a.

FIGS. 4 c and 4 d shows views from the junction of the conductors 43 andthe dielectric/conductive bridge 45 (which is also shown in FIG. 4 a).The dielectric/conductive bridge 45 comprises two layers, a conductivelayer 46 and a dielectric layer 47. When the conductor 43 is notintended to contact the conductive layer 46 of the bridge 45, thedielectric layer 47 is formed on the surface of the conductor 43 and theconductive layer 46 is formed on the surface of the dielectric layer 47.When the conductor 43 should make a contact with the conductive layer 46of the bridge 45 the dielectric layer is omitted from that point.

The technique by which the bridge arrangement is formed may be aflexible printing technique, for instance ink-jet printing. By theprinting technique it is possible to print diverse patterns according tothe need.

In the following, the invention is described by examples:

EXAMPLE 1

A sensor product according to FIG. 1 was manufactured. The electrodesand conductors of the sensor product are of aluminium, and the resistivesheet is a printed area. The electrically conductive element of theprinting ink is carbon.

The manufacturing process of the sensor product comprises:

-   1. The conductors and electrodes can be made by any known aluminum    etching technique by using the following process:    -   a. Resist printing i.e. printing a conductor/s and an electrode        pattern/s to a Al/PET laminate (e.g. PET/adhesive/aluminium)        with a resist ink (e.g. Coates XV1000-2).    -   b. Etching of the Al/PET laminate-   2. A resistive sheet is printed by using conducting carbon ink (e.g.    Dupont 7102) on top of the etched PET-film. The conductivity of the    carbon ink can be adjusted to the desired level by using dielectric    paste (e.g. Dupont 3571). According to the research results, optimal    resistance with a 141×225 mm size sheet is 0.9-1.1 MΩ, measured    between two electrodes which are placed at opposite sides of the    rectangle forming the resistive sheet (the measurement is made in    the length direction of the rectangle, i.e. in the direction where    the longest distance between the electrodes is possible). The    resistance may vary from 10 kΩ to 100 MΩ depending on the size of    the sheet and the application. The carbon printed area overlaps the    aluminum electrodes.-   3. Lamination of a protective layer (e.g. self adhesive PP- or    PE-film).-   4. Die-cutting of the sensor product to a desired format.-   5. Fastening of a connector (e.g. standard Crimpflex connector) by    any standard crimping machine or method.

The resist printing can be made by any common printing techniques, forexample by screen printing (flat bed or rotation), gravure, offset, orflexography.

The etching can be made by any common etching process, for example aprocess based on ferric chloride, sodium hydroxide, or hydrogenchloride.

Any other conducting inks can also be used to form the resistive sheetarea, the conductors and the electrodes. The resistive sheet area can beprinted by any common printing techniques, for example by screenprinting (flat bed or rotation), gravure, offset or flexography.

It is also possible to make the resistive sheet area by using anyconventional coating technology and print or tape, or by other meansfabricate electrodes on top of the coated resistive area.

EXAMPLE 2

A sensor product according to FIG. 1 was manufactured. Electrodes andconductors of the sensor product are of copper, and the resistive sheetis a printed area. The electrically conductive element of the printingink is carbon.

Manufacturing Steps:

-   1. Conductors and electrodes can be made by any known copper etching    technique by using the following process steps:    -   a. Resist printing i.e. printing conductor and electrode pattern        on the copper PET laminate with resist ink (e.g. Coates        XV1000-2).    -   b. Etching of copper laminate (e.g. PET-adhesive-copper).-   2. Resistive area (the resistive sheet) is printed by using    electrically conductive carbon ink (e.g. Dupont 7102) on top of the    etched PET-film. The conductivity of the carbon ink can be adjusted    to the desired level by using a dielectric paste (e.g. Dupont 3571).    According to the research results, optimal resistance with a 141×225    mm size sheet is 0.9-1.1 MΩ, measured between two electrodes at    opposite sides of the sheet in the length direction. The resistance    may vary from 10 kΩ to 100 MΩ depending on the size of the sheet and    the application). The carbon printed area overlaps with the copper    electrodes.-   3. Lamination of protective layer (e.g. PP- or PE-film).-   4. Die-cutting of the resistive sheet laminate to the desired    format.-   5. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Resist printing can be made by any common printing technique, such as,for example, screen printing (fiat bed or rotation), gravure, offset orflexography.

Etching can be any common etching process; for example a process basedon ferric chloride, copper chloride.

The resistive area can be printed by any common printing technique, forexample, screen printing (flat bed or rotation), gravure, offset orflexography.

Any other conducting inks can also be used to form the resistive area,conductors and electrodes.

It is also possible to make the resistive area by using any conventionalcoating technology and print or tape, or by other means fabricateelectrodes on top of the coated resistive area.

EXAMPLE 3

A sensor product according to FIG. 1 was manufactured. Electrodes andconductors of the sensor product are printed with a silver ink, and theresistive sheet is a printed area. The electrically conductive elementof the printing ink is carbon.

Manufacturing Steps:

-   1. Conductors and electrodes are printed with conducting silver ink    on the substrate (e.g. PET film)-   2. A resistive sheet area is printed by using conducting carbon ink    (e.g. Dupont 7102) on top of the etched PET-film. Conductivity of    the carbon ink can be adjusted to the desired level by using    dielectric paste (e.g. Dupont 3571). According to the research    results, optimal resistance with a 141×225 mm size sheet is 0.9-1.1    MΩ, measured between two electrodes at opposite sides of the sheet    in the length direction. The resistance may vary from 10 kΩ to 100    MΩ depending on the size of the sheet and the application). The    carbon printed area overlaps with the silver electrodes.-   3. Lamination of a protective layer (e.g. PP- or PE-film).-   4. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Conductors and electrodes can be printed by any common printingtechnique, such as, for example screen printing (flat bed or rotation),gravure, offset or flexography.

The resistive area can be printed by any common printing technique; forexample, screen printing (flat bed or rotation), gravure, offset orflexography.

Any other conducting inks can also be used to form the resistive area,conductors and electrodes.

It is also possible to make the resistive area by using any conventionalcoating technology and print or tape, or by other means fabricateelectrodes on top of the coated resistive area.

EXAMPLE 4

A sensor product according to FIG. 1 was manufactured. Electrodes andconductors of the sensor product were printed with a silver ink, and theresistive sheet was made of electrically conductive carbon paper.

Manufacturing Steps:

-   1. Manufacturing of conducting carbon paper by mixing the conductive    carbon to the suspension or by coating the paper with conductive    carbon.-   2. Forming rectangle resistive sheet “window” by printing dielectric    (e.g. acrylic based topcoat) to the edges.-   3. Conductors and electrodes are printed with conducting silver ink    onto the dielectric area. Electrodes are overlapping with the    rectangle resistive sheet.-   4. Lamination of a protective layer (e.g. PP- or PE-film).-   5. Die-cutting the resistive sheet laminate to the desired format.-   6. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Dielectric, conductors and electrodes can be printed by any commonprinting techniques, such as, for example, screen printing (flat bed orrotation), gravure, offset or flexography. Any other conducting inks canalso be used to form resistive area, conductors and electrodes.

EXAMPLE 5

A sensor product according to FIG. 2 was manufactured (FIG. 2illustrates a potential sensor product structure for passenger sensingapplications used in smart air bag systems).

Manufacturing Steps:

-   1. Conductors are printed with conducting silver ink on the    substrate (e.g. PET film)-   2. Sensor elements area printed by using conducting carbon ink (e.g.    Dupont 7102) on top of the conductors.-   3. Lamination of a protective layer (e.g. PP- or PE-film).-   4. Punching of ventilation holes-   5. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Conductors and electrodes can be printed by any common printingtechnique, such as, for example, screen printing (flat bed or rotation),gravure, offset or flexography. Any conducting inks can be used to formconductors and electrodes.

The sensor element area can be printed by any common printing techniquesfor example screen printing (flat bed or rotation), gravure, offset orflexography. Any conducting inks can be used to form sensor elements.

It is also possible to etch sensor elements, conductors and electrodesfrom aluminum, or copper.

EXAMPLE 6

A sensor product according to FIG. 3 was manufactured (FIG. 3illustrates a sensor laminate structure for monitoring electricallyconductive objects, for example movement and location of a human body).

Manufacturing Steps:

-   1. Conductors are printed with conducting silver ink on the    substrate (e.g. PET film)-   2. The sensor elements area (the electrically conductive areas) is    printed by using conductive carbon ink (e.g. Dupont 7102) on the top    of the conductors.-   3. Lamination of a protective layer (e.g. PP- or PE-film).-   4. Punching of ventilation holes (optional)-   5. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Conductors and electrodes can be printed by any common printingtechnique, such as, for example, screen printing (flat bed or rotation),gravure, offset or flexography. Any conducting ink can be used to formconductors and electrodes.

The sensor element area can be printed by any common printing technique,for example, screen printing (flat bed or rotation), gravure, inkjet,offset or flexography. Electrostatography is also a usable method. Anyconducting ink can be used to form sensor elements.

EXAMPLE 7

A sensor product according to FIG. 3 was manufactured.

Manufacturing Steps:

-   1. Conductors and sensor elements are etched from aluminum-PET    laminate by using any known aluminum etching technique and the    following process steps:    -   a. Resist printing i.e. printing conductor and sensor element        pattern to the aluminum PET laminate with resist ink (e.g.        Coates XV1000-2).    -   b. Etching of aluminum laminate (e.g. PET-adhesive-aluminum).

Besides etching, electroplating and chemical plating are as wellpracticable.

-   2. Lamination of a protective layer (e.g. PP- or PE-film).-   3. Punching of ventilation holes (optional)-   4. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

Conductors and sensor elements can also be etched from copper by usingany known etching process, such as, for example, ferric chloride orcopper chloride based process.

EXAMPLE 8

A sensor product according to FIG. 4 was manufactured.

FIG. 4 illustrates a sensor laminate structure for monitoring aged anddisabled people. This web structure enables cutting of the web at anypoint between the individual sensor elements because an output forms atthe cutting point. The maximum number of the sensor elements in a sheetis the number of the output lines.

Manufacturing Steps:

-   1. Continuous conductor lines are printed on the surface of the web    with conducting silver ink in the first printing station. The amount    of the conductor lines defines the maximum amount of the sensor    elements in a single row and the shared connection to the    electronics.-   2. Sensor elements area printed by using conducting carbon ink (e.g.    Dupont 7102).-   3. A dielectric bridge is printed in the next process step to    electrically isolate the connection between the conductor lines and    a conductive bridge that will be printed in the next step. A    suitable printing technique for printing the dielectric bridge is,    for example, ink-jet.-   4. The conductive bridge that connects the sensor element to an    individual conducting line can be printed after that by using    conducting silver ink.-   5. Lamination of a protective layer (e.g. PP- or PE film).-   6. Punching of ventilation holes (optional)-   7. Connector fastening (e.g. standard Crimpflex connector) by any    standard crimping machine or method.

EXAMPLE 9

In accordance with example 8, but it is also possible to create aconnection between the sensor element and individual conductor by usingprinted sensor elements or etched aluminum- or copper laminate as asensor element and drill vias trough the substrate material to sensorelement e.g. by using UV-laser. After making vias, conducting lines areprinted with conducting ink to the reverse side of the laminate.Conducting ink fills the vias and creates contact between the conductorand sensor element.

EXAMPLE 10

In accordance with example 8, but it is also possible to create aconnection between the sensor element and output by using group oflinear continuous lines parallel to the web on the backside of thesubstrate while the electrically conductive sensor elements are formedon the front side. The parallel conductors on the backside can be formedby etching or printing or by laminating of a flat cable on the backsideof substrate. The contact between single conductor line on backside andsensor element on the front side is formed in two steps:

-   1. vias are drilled (e.g. by using UV-laser) through the substrate    to a single continuous conductors on the back side at the    perpendicular location of sensor elements, and-   2. conductors printed with conductive ink on the front side of    substrate perpendicular to the web across the via and the sensor    elements, and the ink fills the vias and creates contact between the    single backside conductor and the front side sensor element.

1. A sensor product web for electric field sensing, the sensorcomprising: a substrate comprising a continuous roll of material; aplurality of sequential electrically conductive areas on a surface ofthe substrate; a plurality of conductors arranged on the surface of thesubstrate; an output connected to one of the electrically conductiveareas by one of the conductors; a plurality of dielectric layersarranged on top of the conductors, wherein one of the dielectric layersis arranged in the vicinity of each electrically conductive area; and aplurality of an electrically conductive layers arranged on top of thedielectric layers on a same surface of the substrate as the electricallyconductive areas, each of the electrically conductive layers extendsbetween the one of the electrically conductive areas and the conductors,and the dielectric layer being discontinuous at one of the conductors,thereby resulting in an electrically conductive path between one of theelectrically conductive areas and one of the conductors, therebypermitting the cutting of the substrate at a plurality of points to formoutput including at least one electrically conductive area and at leastone associated conductor.
 2. The sensor product web according to claim1, wherein the electrically conductive area comprises a printed orcoated layer.
 3. The sensor product web according to claim 1, whereinthe electrically conductive area comprises a plastic layer, or a fibrouslayer.
 4. The sensor product web according to claim 1, wherein theelectrically conductive area and the conductor comprise metal,conductive carbon, or electrically conductive polymers.
 5. The sensorproduct web according to claim 1, wherein the sensor product comprises atop layer comprising a film of plastic material, paper, or board, or adielectric coating.